USE OF METAL O-RINGS FOR SEALING IN EXTREME CONDITIONS.

Rings are suitable for use where pressures or temperatures, or both, are very high or fluctuating, but they are also used for sealing vacuum systems and at cryogenic temperatures. The four types in common use are: solid, hollow, gas-filled, and pressure-actuated. Mild steel rings of En2 are mostly used, but stainless steel type 316 or 321, or Inconel are also employed. Copper, cupro-nickel or Monel rings are available for special applications. The rings may be indium, cadmium, nickel, copper, silver or gold plated. Fluorocarbons such as PTFE are often used as coatings.